Ask a room of canvas printers whether to coat before or after stretching and you will probably get both answers. Each approach works, and each has its own risks. What matters is understanding the trade-offs so you can choose the method that fits your workflow and your media.
Coating before stretching
Here the print is coated flat on the table, or run through a coating machine, and stretched once the coating has cured.
- Even coverage: a flat sheet is easier to coat consistently, especially with a roller or machine.
- Protected wraps: the edges that fold around the bars are coated too, so they are protected during stretching, which is when they are most likely to be scuffed or marked.
- Efficient batching: several prints can be coated in one session and stretched later.
The main risk is cracking at the corners and along the folds. When the canvas is pulled tight around the bars, the coating has to flex with it. Whether that is a problem depends on the coating, the canvas, the ink load and how thickly the coating was applied. Thinner coats generally flex better. Test by coating an offcut, letting it cure, then folding it as tightly as you would on a stretcher and checking for cracking or whitening.
Coating after stretching
Here the canvas is stretched first, then coated on the frame, usually by brush, roller or spray.
- No cracking at folds: the coating goes on after the canvas has been shaped, so it is not flexed afterwards.
- Seals any handling marks: scuffs from stretching are coated over rather than left exposed, although marks will still be visible.
- Suits one-offs: convenient for single gallery wraps and small runs.
The downsides are that it is harder to get an even coat on a slightly springy surface, the edges and corners need careful attention, and drips can run down the sides. Spraying, including aerosols such as ClearJet, is often the easiest way to coat stretched canvas evenly, including the wrapped edges.
A way to decide
- Print a test canvas with heavy ink coverage running across the wrap.
- Coat half flat, let it cure fully, then stretch it.
- Stretch the other half uncoated, then coat it on the frame.
- Compare the corners, edges and overall evenness once both are fully cured.
If the flat-coated half stretches without cracking, coating before stretching is usually more efficient for volume work. If it cracks, coat after stretching, or reduce coating thickness and test again.
Whichever you choose
Make sure the print has fully dried and outgassed first, work in a ventilated area away from ignition sources, and follow the coating’s data sheet. Our compatibility page covers which inks suit our coatings.
Seeing cracking on your wraps, or want a view on the best method for your canvas? Call 01252 624 411 or use the contact form.